Refrigeration system



Sept. 28 1926. 1,501,445

G. HILGER REFRIGERATION SYSTEM Filed NOV. 22, 1924 Patented Sept. 28 1926.

UNITED STATES GEORGE HILGER, OF CHICAGO, ILLINOIS.

REFRIGERATION SYSTEM.

Application filed November 22, 1924. Serial No. 751,449.

In certain of its aspects, my invention pertains to a refrigeration system employing one or more expansion elements or coils, in combination with a control valve operable automatically under the control of the temperature of the refrigerant returning to the compressor, to regulate the flow of refrigerant to the expansion element; and one of the objects of the invention is to provide, in conjunction with such a temperature responsive valve, an automatic pressure reducing valve operating to supply to the temperature responsive valve refrigerant at a reduced substantially constant pressure, whereby to render the temperature responsive valve sensitive to relatively slight changes in the temperature of the returning gas.

The invention also has special reference to a refrigeration system of the type having a plurality of refrigerating units which it is. desirable to control independently; and a further object of my invention is to provide automatic means for maintaining such units at all times at maximum efliciency, in combination with means also operating automatically to maintain a supply of refrigerant for the several units, at a predetermined pressure, sufficient only to meet the requirements at any given time, thus effecting a reduction in 'the amount of the, refrigerant consumed and a consequent saving of power in the operation of the refrigerating machine.

A further object of my invention is to provide an improved refrigeration system in which any one of a plurality of refrigeration units may be controlled independently of and without disturbing the operation of the other units, either manually or automatically.

Another object is to provide a system in which any one of several refrigerating units may be defrosted independently, without disturbing the operation of the other units and in a manner such as to reduce the condenser pressure with a corresponding reduction in the power, consumed.

Still another object is to provide in' a refrigeration system means whereby any one of a plurality of refrigerating units may be pumped out or exhausted of the-refrigerant independently of the other units, to perm t of the making of repairs and the like.

In the preferred embodiment of my invention illustrated, I em loy a system of headers one connected with the discharge side of a compressor, another connected with the suction side of the compressor and a third header adapted to be connected with either the discharge or suction sides of the compressor. A pressure operated expansion valve of ordinary or preferred construction operates to maintain in the first or charging header a predetermined pressure, and the flow of refrigerant to each of the several refrigerating units from said charging header is under the control of a valvegoverned by the temperature of the refrigerant returning from the given unit to the second or suction header. The third or combination defrosting'and pumping-out header is in valve-controlled communication with the return side of each of the refrigerating units and is arranged to be connected under the control of suitable valves either with the discharge s de of the compressor for defrosting purposes or with-the suction side of the compressor for pumping-out purposes. The automatic temperature controlled valve for each of the units is of the general character described and claimed in my copending application Serial No. 737,455.

In the accompanying drawings, Figure 1 is a fragmentary perspective View partially diagrammatic in character of a refrigeration system embodying my invention.

Fig. 2 is a fragmentary vertical sectional view through a pressure-operated expansion valve of preferred construction.

Fig. 3 is a similar View through the temperature controlled valve employed for each .of the refrigerating units.

The systeni in itsv preferred form comprises a compressor A of a suitable character, a condenser B and a liquid receiver C. The compressor has a discharge pipe 4 with which is connected a pipe 5 leading to the condenser. The condenser in turn is connected by a pipe 6 with the liquid receiver, and the latter is connected by a pipe 7 with a pipe 8 of relatively large size constituting the charging header. The pipe 7 has a hand operated valve 9 interposed therein and also an automatic primary expansion valve 10, the latter being interposed between the valve 9 and the header. This valve 10, shown in detail in Fig. 2, may be of any suitable construction, being under the control of the pressure at the discharge side of the valve so as to maintain the latter substantially constant. It comprises briefly, in the present instance, a casing 11 having at its upper portion a through passageway controlled by a valve member 12. The valve member is connected with a diaphragm 13, and a coiled expansion spring 14 enclosed in the lower portion of the casing maintains a predetermined pressure on the diaphragm which is counterbalanced by the pressure on the discharge side of the valve. 'By'adjusting the spring tension the pressure on the discharge side of the va'lve and in the present instance in the'header 8 may be readily varied.

I have herein shown diagrammatically three roomsor chambers R, R and 'R each containing a refrigerator unit or coil '15, the lower end of which is connected'by a pipe 17 with the charging header 8 and 'the upper end of which is connected by a pipe ,18 with a large pipe 19. The latter is connected by a pipe 20 with the suction side of the coin-' pressor and constitutes the suction header .offlthe system.

The supply pipe 17 for each of the coils I is provided with suitable .valve means whereby the unit may be cut out of the system at will. Herein 'I "have shown a simple hand operated valve 21 in each of said pipes for'this purpose.

The primary expansion valve serves to maintain in the charging header -8 a supply of refrigerant .at a predetermined pressure sufi'icient to meet the requirements of the several units, this pressure-being determined by the lowest temperature which it is'desired to'ma intain inlany one of the roomsor chambers. To control'theflow of refrigerantthrough-the several units from the charging header in a manner such as to supply that volume of refrigerant only .Which the unit is capable of evaporating, .I provide an automatically operating valve generally designated by the numeral 123. This valve is ofthecharacter shown in ;detail in Fig. '3, being so constructed as to operate to check the How .of refrigerant-to the coil when thetemperatureof the refrigerant at-the discharge end of-the coil falls below a predetermined point.

.Pre'ferablythe .valve comprises a casing2 l having in itsupperportion a through passageway controlled bya valve25, which passageway .is connected in the pipe line 17 leading to the coil. The lower portion of 'the casing is constructedtoprovide a jacket .26 interposed in'the;pipe,l1ne '18 connected 'with the-return side'of the coil.

The -j acket 26 partially surrounds-a chamber 27-in-the 'casin'g, one wall -of 'said chamber being formed byaninsulating diaphragm 28 ope-ratively associated-withthe valve 25. Inthe chamber 27 is-contained-a quantity-of-am monia or ,the'like, which being subjected to the temperature of the refrigerant'leading from the coil exerts a greateror less pressure oaths-diaphragm 28 tending to open the valve against the pressure of the refrigerant in the feed pipe 17 plus the action of a spring tensioning means generally designated 29. By adjusting the spring tension the pressure of the ammonia in the chamber 27 at which the valve 25 will close its passageway may be readily determined so as to supply to the coil only that volume of refrigerant which it is capable of evaporating. Thus when the coil is entirely frosted the temperature of the refrigerant passing through the jacket 26 effects a suiticient reduction of pressure :lIl the chamber 27 to checkthe flow of refrigerant to the coil preventing a freezing 'back'tothe compressor.

It-willbe seen that-the .gas in the chamber 27 is not influenced by the temperature-of the refrigerant in the upper portionof the casing due to the presence of the insulation in the diaphragm 28. This is of Vital importance for the .reason that the valve in order --to be-operative-must be set -to operate under a fixed temperature 'difl'erence between the temperature and pressure of the refrigerant'passing t-o-the coils-and the-temperature of the refrigerant returning from the coils, and if subjected to variable disturbing influences such .asthe temperature of-the ehamber'being cooled or-the-temperature of the refrigerant passing to the coils, the valve will obviously fail :to operate as intended.

Also, it is 'to be noted that the chamber 27 is independent of the pressure of the refrigerantreturning -to the compressor and passing 'through the jacket 26. Consequently the expansion element -in the chamber 27'is governed solely'by thetemperature of. the refrigerant passing through the jacket. Also -v-ariations in the temperature of the returning refrigerant are-transmitted -to the expansion element in the chamber 27 only gradually due-to the time'interval required for the transmission of heat through the wall of-the chamber 27- This is essential *for the reason that a sudden increase of pressurein the chamber 27 due-to the pass age-of super heated gas I through the jacket 26 Would-serveto open'the valve 25 and allow-the passage of-more refrigerant 'to the coil than-"the coil could evaporate. 'Inother words, -it would result in the fiooding of the system, with an attendant waste.

By retarding the operationof the walve it is enabled to control the flow ofrefrigerant to the coil in accordance with the volume :which it is eapablelofevaporating.

-valve 10 so that the predetermined pressure -in the charging header ismaintained. ":An important -advantage is gamed .as a result of the maintenance in the charging header of this reduced pressure as dlstinguished from condenser pressure which not only varies as the temperature of the cooling water employed in the condenser varies, but isnormally so high as to render the temperature responsive valve impractical. Thus, with a condenser pressure of from 150 to 200 pounds, this pressure applied to the top of the valve member would necessitate the production in the thermal chamber of the valve of a correspondingly high pressure to open the "alve. As a result, as soon as the pressure in the thermal chamber had overcome the pressure on the topof the valve so as to lift the valve slightly, the condenser pressure passing around-the valve, and so admitted to its 'under side, would cause the valve to move suddenly into a wide open position. Thus, it will be seen the valve will operate with a jerky hammerlike action. Moreover, such movement of the valve'member into wide open position would admit refrigerant at condenser pressure to the coil, at a much'higher rate than the refrigerant is capable of evaporating, and heavily saturated refrigerant would be returned to the compressor before the pressure in the thermal chamber could be reduced sufficiently to check it. On the other hand, by reducing substantially the pressure supplied to the temperature responsive valve the difference in pressures operating the valve .is relatively small so that the latter is very sensitive and effective to control the flow of refrigerant as intended.

The normal operation of the system involving a plurality of coils or other expansion elements is as follows: Assuming that it is desired to maintain the several rooms R, R, and R. at varying temperatures, the

expansion valve 10 is adjusted to maintain a pressure in the charging header 8 such' that the temperature thereof is somewhat below the lowest temperature which it is desired to maintain in any of the rooms. The valves 21 leading to the several units being open, refrigerant is supplied simultaneously to all of the coils. As soonas any one of the co-ilsbecomes entirely frosted and reaches a condition such that it is evaporating the maximum amount of refrigerant of which it is capable, a reduction in pressure occurs in the chamber 27 'of the valve, which checks the flow of refrigerant to the coil feeding only that volume which will maintain the coil operating eiiiciently. Then the desired room temperature has been reached,the operator closes the proper valve 21. The other coils, however, continue to operate undisturbed by the cutting off of the one coil until finally the desired room temperatures are obtained in their res ective chambers when they too are cut 0 by the operation of their valves 21. In any case the decrease in the volume of the refrigerant consumed reduces the amount of work required to be performed by the refrigerating machine.

It will. be understood that by adjusting the pressure and temperature of the refrigerant in the charging header in accordance with but slightly below the lowest temperature to be attained in any room, the valve in this case will operate just as in the case of the other rooms because then the temperature of the returning refrigerant, even though the same as the room temperature, will be higher than; the temperature of the refrigerant entering the coil. 1

Furthermore such adjustment of pressure in the charging header will insure that the pressure of the refrigerant returning to the compressor from the coil of a room to be maintained at a relatively high temperature,

will not be higher than the pressure required to cool the coldest room and hence not high enough to enter its coil from the return side after passing from the' coil of the high temperature room. For example a condition frequently met with in practice, is that where several rooms must be maintained at varying degrees of temperature. Thus for the sake of illustration, it may be assumed that it is desired to maintain chamber R" at a temperature of 30; room R at a temperature of 20; and room R at a-teinperature of 10, and that these temperatures have risen slightly in each case so that the rooms require further refrigeration. Now if the refrigerant were supplied to the valve 23 of each of said rooms at a pressure higher than that required for 10 (the temperature of the coldest room R) the pressure discompressor with the result that considerable damage would result to the compressor such as knocking out the head. On the other hand it will be seen that by the provision of the regulatingvalve 10 adjusted 1 with regard to the temperature of the coldest room such an occurrence could not take place. 4

Thus, the valve lfl-ope'rates to maintain a Suppl of refrigerant'at a proper predeterminecf pressure available to each of the refrigerating. coils or units, and the'valves 23 operate to insure that the. individual coils shall be maintained at all times at their maximum efliciency, feeding the maximum in combination .with .a control valve for each coil .is advantageous because a sudden or sharp reduction in pressure such as would be [effected by .the .use of a single valve would result in a wire drawing of the refrigerant which ,is objectionable because of an attendant cutting action onthe valve and .its seats producing excessive .wear and irequiring frequent :repairs. With applicants arrangement .the expansion .valve' operates to reduce the pressureonly partially, while the control \valve effects a further pressure reduction as determined by therequirements of the system- Consequently neither valve is required ,to make sharp Ipressure Ireduc- ,tions as is necessary when .only one valve is used.

,Still anotheradvantage is thata constant pressure maintained in ,the charging header renders it unnecessary from time to .time toreset the ,valve 23. Thecondenser pressure varies with changes in the season because the temperatureiof the cooling water employed ,for thetcondenser correspondingly vchanges. Thevalve 1O insures that the pressure in thecharging header shall be independent ,of or unaffected by changes in ,the condenser pressure.

The system thus far described lends itself .readlly'to the use of a third header forpurposesof,defrostingianyone or more of the refrigerating units without interrupting the operation of the system as a .whole or for the purpose of pumping" ut or exhausting oneor more of the units.- his third header .1s also n the form of apipe designated 30 and herein shown as extending parallel to the p pes 8 and l9 constituting the.charging and suction headers. This ,pipe 30 is connected with each of the return pipes .18 through the ,medium of a hand operated three-way valve 31. ,Also it is adapted ,to be connected with either the discharge or suction sides of the compressor by means of a pipe 32 havlng branches 33 and-34 respect velyconnected with the discharge and suc- ;t1on lines 5 and 20. Ahand operated valve 35 lsadapted to control communication ,be-

tween thedischarge side of thecompressor and the pipe 30, and a hand operatedthree way-valve 36 selectively controls communication between the suction side ofthe compressqrand either the pipe 32 orthe suction lme 20.

It frequently happens. that .therefrigerating coils become coated .with layers of snow and ice which serve ,as insulators preventchar-gin operate s me ingthe absorption of heat from the room beingcooled by theevaporating refrigerant in ,the coil. Thisis especially true when the room is used for cooling products having a tendency to give off vapor when placed in the cooling \room. As a result it becomes necessary to remove the coating of me or snow as the case may be and the method commonly employed is to strike the coil with a suitable implement cracking off the ice and allowing it to fall to the floor. This ice has thus beenitheicause of considerable annoyance and moreover is a source of waste not only from the standpoint of the power consumed in producing it but also because it reduces the .efiiciency of the sys tem. By means of the construction and arrangement which I have provided it is possible to effect the removal of the ice by passing the refrigerant directly from the compressor and hence in a heated state to the coil. This is accomplished without disturbing the normal operation of the other coil by opening the valve 35 so as to allow a portion of therefrigerant discharged from the compressor to pass directl into the header 80and intothepipe .18, the valve 31 having been operated to open communication between this pipe and the header 30 and incidentally to cut off communication between the pipe 18 and the suction header 19. The hot refrigerant passing directly from the compressor to the pipe 18 and through the valve jacket 26 quickly causes the valve 23 to open. Further, the valve 21 in the ;pipe 17 is left open so that the refrigerantpasses through the refrigerating coil, thegsupply pipe -17 and into the charging header 8. Owing to the ;presence of the valve 10the pressureinthe charging header is substantially less thanthe pressure in the pipe 18 now connected directly with the compressor and the cutting out one of the coils from refrigeration reacts upon the valve 10 so thatihe latter operates'to maintain in the charging header ,the predetermined constant pressure. It will be observed that n such passageo'f this portion of the refrigerantthroughthe coil 15, not only is the ce on the coil m'elted, but in so melting it coolsthe-refrigerant rendering it unnecessary to pass the refrigerant throughvthe condenser. Thisefiects a reduction in the condenser pressure with a consequent saving in the power consumed .duringthe defrosting operat on.

In the event that one of thecoils is in need of repair or for any other reason it is desired to exhaust'it, this may be accomplished by connecting the return pipe 18 fonthat coil with the suction side of'the compressor. In such event the valve 21 is closed to cut off communication,between the.coil and the header 8; Also the valve 31 is ,to establish communication between the return pipe 18 and theheader while cutting ofl communication between the pipe 18 and the suction header. The valve is closed-and the valve 36 operated 1 to establish communication between the pipe 32 and the pipe 20 leading to the suction side of the compressor while cutting off communication between thecompressor and the suction header 1?. Thus the compressor opcrates to pump out or exhaust the refrigerant from the coil 15 twhich has been connected to the header 30, the other coils remaining idle during, this operation. Pumping out requires only a short time inasmuch as the full suction effort of the compressor compressor to the suction header herein shown manually operable valves 21 for cutting off several coils as desired, temperature responsive shut off valves such as are well known in the art may be employed for this purpose if desired. Also it will be understood that the invention is not limited to use in coolers where the surrounding medium to be cooled is air, but that it is equally applicable to use where the medium to be cooled is of a different form such, for example, as brine.

I claim as my invention:

1. A refrigeration system comprising, in combination, a compressor, a condenser into which the compressor discharges, a pipe line 7 leading from the condenser, a charging header, an automatic expansion valve controlling communication between the pipe line and the charging-header and operating to maintain a reduced substantially constant pressure in the charging header, a plurality of refrigerating coils connected with the charging header and with the suction side of said compressor, and a valve for each of said coils adapted to feed refrigerant from the charging header to the respective coils, said valve having temperature responsive means operating automatically to limit the volume supplied to the maximum which the coil is capable of evaporating.

2. In a refrigeration system the combination of a compressor, a con-denser, a charg-' ing header communicating with the condenser and a suction header communicating with the compressor, 'a' plurality of coils connected to said headers in parallel arrangement, a primary expansion valve operating automatically tov maintain in the charging header'a supply of refrigerant at a substantially constant pressure, andmeans including a temperature responsive valve operating automatically to control the volume of refrigerant supplied to the individual coils from the charging header in accordance with the maximum which such coil is capable of evaporating.

3. In a refrigeration system, the combina-. tion of a compressor and a condenser, a charging header communicating with the condenser, asuction header communicating with the compressor, a plurality'of coils each having a supply pipe connected with the charging header and a return pipe connected with the suction header, means for maintaining in the charging header a reduced substantially constant pressure and a control valve for each coil comprising a casing having a valve-controlled passage interposed in said supply line and a second passage interposed in the return pipe, and means in, the casing responsive to the temperature of the refrigerant passin through the second mentioned passage for operating said valve whereby to control. the volume of refrigerant supplied to thecorresponding coil.

4. A refrigeration system comprising, in combination, a compressor having a suction line and a discharge line with a condenser I therein, a charging header in communication with said condenser, a suction header in communication with said suction line, a plurality of refrigerating coils connected at their opposite ends with said charging and suction headers respectively, and a third header in valve-controlledcommunication with the return side of each of said coils and with' either sai suction line or said discharge line at a poin between the condenser and compressor.

5. A refrigeration system comprising. in. combination, a compressor, a condenser, a high pressure line connecting said compressor and condenser, a suction header leading to said compressor, a charging header lead ing from said condenser, an expansion valve located between said condenser and charging header and operating automatically to maintain a reduced substantially constant pressure in said charging header, a plurality of refrigerating coils connected to said charging header'and suction header, a valve for each of said coils regulating the flow of refrigerant in accordance with the refrigerating requirements of its coil, and valve-controlled means for connecting said high ressure line to the return side of said coils independently, whereby to pass hot gas from said 'high pressure line through. the selected coil reversely into said charging Y header.

matic expansion valve'in said feed line operating to supply refrigerant at a constant pressure substantially below the compressor pressure, a plurality of refrigerating coils, temperature responsive valves operating to control the flow of refrigerant from said feed line to each of said coils, and meansfor connecting the discharge side of said compressor to the outlet of any of said coils whereby to force hot compressed refrigerant reversely through the selected coil into said feedline.

7-. A refrigeration apparatus comprising, in combination, a compressor, a refrigerant circulating system connected with the discharge and suction sides" of the compressor and having interposed therein means for cooling the refrigerant discharged from the compressor, an expansion coil interposed in the circulating system, a constant pressure expansion valve operating automatically to reduce the pressure of the cooled refrigerant tobe supplie'dto said coil, and m'eans interposed in the feeding and return sides of said system responsive to the temperature of the refrigerant returning to the compressor and operating to control the volume of refrigerant supplied to'said coil;

8. In refrigeration apparatus, the coml'ii'natibn' of a circulatory system including a compressor and a condenser, a plurality of coils connected in said system, an expansion valve 0 crating automatically to maintaina' Suppl of refrigerant available to all of said coils but at a reduced substantially constant pressure, and valve means controlled by the" temperature of the refrigerant returning'to the low pressure side of the system for further governing the flow of refrigetan'fi to said co'i'l's.-

95 refrigeratingsystem having, in combin'ation, a? compressor having a suction line and a'dischargeli-ne with a'condenser therea se 1 4m;

coil and either the conductor or the suctionline selectively, and valve-controlled means for establishing suction-side of said compressor and either the suction line or the conductor.

10. A refrigeration apparatus comprising,

in combination, a compressor, a refrigerant circulating system connected with the discharge and suction sides of the compressor and having interposed therein means for cooling the refrigerant discharge from the compressor, an expansion element interposed in the circulating system, an automatic constant pressure reducing valve operating to maintain a supply of refrigerant available to said expansion element at a reduced substantially constant pressure, andivalve means controlled by the temperature of the refrigerant returning to the low pressure side of the system for further regulating the flow of refrigerant to said expansion element.

11. The method of operating a refrigeration system of the direct expansion type which consists in maintaining a supply of cooled refrigerant at a substantially constant pressure substantially lower than con denser pressure, and discharging the refrigerant from such source of supply into an expansion element such as a coil While regulating the flow of the refri erant to the coil to the maximum which thecoil can evaporate as determined by the temperature of the refrigerant returning from the coil.

Intestimony whereof, I. have hereunto affi'x'ed my signature;

GEORGE HILGER.

communication between- 

